What are some of the reasons for considering tunneling options when deploying IPv6?

What will be an ideal response?

Reasons you might consider this method as part of your deployment are:
* IPv4 network devices don't support IPv6.
* You're not permitted to modify the hosts to configure IPv6 for any number of reasons, such as lack of downtime window, regulatory restrictions, or the fact that you do not own or control the devices.
* You need to enable connectivity quickly between two or more isolated groups of hosts.